This invention relates to motion transmitting devices for effecting speed cRanging or torque conversion between a rotary input and a rotary output.

In conventional gearing, the torque is transmitted through one tooth, at a time. In U.S.Patents Nos. 4,023,440 and 4,194,415 and also in U.K.Patent Application No.8,Oil,06 , tϋere are described means by which, up to one quadrant or 25% of the teeth in a gear pinion can be lept in driving engagement in a motion transmitting device. ^' These devices have become known as "Quadrant Drives". Also the aforementioned U.S. Patent No.4,194,415 and U.K.Patent Application No.8,011,061 describe ow it is also possible to get pure rolling motion between all the drivingly engaged parts of the whole motion transmitting device.

It is an object of the present invention to provide a motion transmitting device forming a significant advance over the devices- mentioned above by a still

OΪ.ΪPI ^l

further increase in the proportion of -meshing elements in driving engagement. As- will _he apparent from the following description, it is possibe in some constructions to obtain a 36O° or 100% engagement of all the meshing elements that are drivingly engaged in the motion transmitting device and to Have these meshing elements engaged all of the time whilst also producing a change of speed or torque conversion between the input and the output. In preferred embodiments of the invention, all of the meshing elements that are engaged all of the time are connected by pure rolling motion, in order to keep friction to a minimum. -B Raving 100% of the meshing elements- engaged 100% of the time, it will be shown that enormous increases in torque capacity become possible.

In. order to obtain 100% engagement of all the meshing elements 100% of the time, the present invention makes use of two features. Firstly, one of the torque transmitting elements is male and the other female, so that one will embrace the other. Secondly, the internal diameter of the female element is effectively equal to the external diameter of the male element. Unless the above two conditions are catered for, it is not possible to get continuous 100% contact about the circumference of the respective elements.

The above requirements at once produce a dilemma, since in order to achieve a change of speed, or torque conversion, it is necessary to have a difference in diameters Between the meshing elements. In the prior patent specifications referred to above, in order to achieve multi-tooth engagement, each individual torque transmitting element in the speed changing devices only move in one plane with two degrees of freedom of motion. If a speed changing device can - e designed in ich some of the meshing elements are capable of moving in two planes with three degrees of freedom of motion, .then it is possible for all the torque transmitting meshing elements to be drivingly engaged all of the time. A well-known mechanical device which is inherently capable of three degrees of freedom of motion in two planes is a swash plate. Even if the swash plate is locked in order to prevent • it from rotating about the axis of the drive shaft which is causing it to swash, any point on the surface of the swash plate will describe a path on the surface of a sphere, which path is composed of three degrees of freedom of motion in two planes. At a point on the surface lying on a normal to the axis of the drive shaft causing the swashing motion, if the axis of the shaft passes through the centre of the sphere

OMPI

and if the normal passes through the centre, this path is a very elongate spheroidal figure of eight. The proportions of this figure of eight are a function of the angle of swash. As the generating point is moved away from the position on the normal, this spheroidal figure of eight gradually changes and eventually becomes a circle when the generating point is on the axis of the drive shaft. These shapes will always be generated for every revolution of the ^* drive shaft which causes the swash plate to swash.

It is well known in constant velocity joints to make use of balls as movable meshing elements between a male and a female member. Such joints however provide ^' unity speed ratio. It has been proposed in U.S. Patent Specification No. 2559093 of Rzep a to provide an angle coupling for coupling shafts in a fixed angular relationship, more particularly for connecting an obliquely arrayed steering wheel for a motor vehicle with a stem extending through a vertical post and which makes use of balls located in sockets in a part-spherical female member, the balls engaging also a zig-zag groove on a part spherical meshing member to give a non-unity velocity ratio. However the sockets in the part spherical female member hold the balls in position sc that this member is a cage for the balls as well as a torque transmitting member, the balls reacting against

.P

he walls of the sockets in the cage. This results in a sliding or skidding motion between the balls and the walls of the sockets. Pure rolling motion is not possible and this device will not operate efficiently at high speed.

According to this invention, motion transmitting apparatus comprises a male member, a female member, swashing means and a plurality of freely rotatable meshing elements between part-spherical surfaces of the male and female members, the meshing elements engaging in an endless wavy groove in a part-spherical surface of at least one of said members, which groove is arranged so that relative swasing motion of the male and female members causes the meshing elements to precess along the. wavy groove, whereby torque is transmissible between said members through said meshing elements, said meshing elements being freely rotatable in the other member or in rolling engagement therewith. In a preferred form of construction, the meshing elements are balls and, in this case, said wavy groove must have a number of waves which differs by unity from a multiple of four.

In an alternative arrangement, the meshing elements are spindles journalled in roller bearings in said other member, and, in this case, the wavy groove on said one

G PI

me ber must have an odd number of waves.

If balls are employed, they may be arranged to roll each in a separate arcuate groove on the part- spherical surface of said other member or the balls may be arranged to roll in an endless wavy groove extending around the part-spherical surfaces of said other member and having a number of waves also differing by unity from the aforesaid -multiple of four, the numbers of waves in the grooves on the two menbers differing by two.

In accordance witR one aspect of the present invention, a motion transmitting device comprises Cal swashing means-

Cbl meshing means in the form of a series of independently movable meshing elements whose centres are constrained to remain on the circumference of a swashing circle Ccl swash plate means formed with a circumferential wavy groove, said groove Being partially complementary to said meshing elements Cd] a series of individual movement-limiting means, incorporated in a datum means, wherein said swashing means is disposed to cause said meshing elements to preceεs around said circumferential wavy groove in said swash plate means, each of said individual movement—limiting means guiding in captive dependency alwa s the same individual meshing elemen- within specific limits of arcuate oscillating motion, said

arcuate oscillating motion of the centres of said individual meshing elements being in two degrees of freedom of linear motion relative to eac of said individual movement-limiting means, but being in three degrees of freedom of linear motion relative to said swash plate means.

According to another aspect of the invention, a motion transmitting device comprises

(a) an input, an output and datum means, one .of which is a first shaft, another of which is a second shaft and the third of which is a frame, said first and second shafts being separately relatively rotatable with respect to the frame about a common axis, (b) a male member and a female member, at least one of which members is angularly movable about orthogonal axes which are orthogonal to and intersecting said common axis at a common centre, (c) one of said male and female members being coupled to said first shaft by first coupling means and the other of said male and female members being coupled either to said frame or to said second shaft by second coupling means, (_) the coupling means for the or each of said male and female members which is angularly movable about orthogonal axes including swashing means,

OΪ:?ι

(e) a plurality of meshing, elements between the male and female members, said meshing elements being located on one of said members by a circumferential guide having waves, the number of waves being (n-11 or (n+1] where n is an integral multiple of four, and said meshing elements being constrained by the other of said members to be each at any or all of the respective ones of a plurality of locations, (f} said locations Cil being points arcuately spaced 360 degrees apart on a part-spherical n surface around said common centre, or

(ii) being guides along arcs of median lines on a part-spherical surface about said common centre, which median lines pass through said points, or (iii) being a -wavy circumferential guide or guides of the same wave amplitude as the waves of said one member with the median lines of the waves passing through said points, each wavy circumferential guide extending around a part-spheroid of said other member, the number of waves around the circumference being (n+1) or (n-1) according as the number of waves on said cne member is (n-1) or (n+1 ^* so as thereby to differ by two therefrom, whereby the meshing elements form a coupling between the male and female members, causing one to precess

relative to the other with simultaneous relative swashing motion and so causing one shaft to rotate relative to the other and so thereby transmitting rotary motion from said input to said output at a changed speed.

The guides are conveniently grooves in part- spheroidal surfaces of the male and female members and the meshing elements are balls engaging in said grooves although, as will be explained later, in some embodiments the meshing elements may be fixedly located in one of the members, e.g. they may be pins journalled in one of said members.

It will be noted that in the above described construction, there is necessarily a wavy circumferential groove or grooves on one meπfcer. The πeshing eleitents are either fixedly located or are guided with respect to the other member. If the meshing elements are fixedly located, they are at points spaced 360 degrees apart as stated above. If guides on said other member in the form of grooves are employed these may be arcs of median lines on a part-spherical surface (in which, for reasons which will become apparent, the device is referred to as a simplex device) or the guides may be a wavy circumferential groove or grooves. This latter arrangement having two wavy grooves or sets of wavy grooves, with the number of waves differring by two, as described above, is referred to as a duplex or compound construction.

The n-umber of balls or other meshing elements

is preferably n although the device will operate if

one or some are omitted. It is desirable to use the

maximum number n of balls to ensure the maximum

torque-handling capacity.

The meshing element in the torque converter

described above may be balls or like elements between

a male member and a female member. In certain of

the embodiments, as will be described in the following

specification, it is possible to obtain pure rolling

motions of balls in axial grooves in the female member

and in circumferential wavy grooves in the male

member, the balls constituting the coupling between

the male and female members, which members may be the

input and output. The male and female members

typically are part-spherical.

In specific embodiments, this pure rolling motion

is achieved in two ways. Firstly because the distance

of the path along which the ball has to follow between

crest and hollow of a wavy groove is greater, since the flank of the wave is at an angle, than the axial distance of the grooves, but since the wave is on the male and therefore the contact point of the ball is radially further in, yet the contact point of the ball in the grooves is radially further out, these two rolling distances can be equated.

Secondly, because the above is only an average condition since the points on the wave, they are points on the surface of a sphere , are points which at an instantaneous moment in time are travelling in the path of a great circle although constantly changing the choice of a great circle. The flank of the wave is not itself a median line on the sphere but is a complex wave form made up of an infinite number of great circles. A second instantaneous equalisation of rolling velocities of the balls when in contact with the male and female elements can be achieved, if necessary, by altering the cross- section of the grooves i the male and female elements thus causing the balls to rise and fall in the grooves to alter the effective radial point of contact thus altering the ratio and thus achieving equal constant instantaneous rolling velocities of the balls on the surfaces of the male and female elements.

The torque converters in some specific embodiments to be described are torque converters having a high torque multiplication ratio, which may be a step up or step down ratio. This may be achieved by holding one of said male or female elements fixed, the other one of these two elements being either the input or output to drive or be driven by the third element of the torque converter.

The present inventionincludes within its soope constructions in which the male and female elements constitute the input and output. In this case a low torque multiplication ratio would be obtained. By mounting these elements directly one on the input and the other on the output, the device can be used for coupling two shafts at an angle to one another. Because pure rolling motion of the balls can be obtained as described above, it becomes possible to use the device as a high torque high efficiency and high speed fixed angle drive and low ratio torque converter. It is not possible to obtain pure rolling motion in a conventional constant velocity universal joint because the point of rolling contact of the ball on the male element is radially further in than the point of contact on the female, which is racially further out and, in order to get a constant velocity ratio, the median line of the balls must swash at half the angle of deflection of the joint. This swash angle does not correspond to the condition giving the speed at which the balls wish to precess in the epicyclic sense in, for example, a ball thrust bearing. Hence, the rolling distances

are different and slipping will occur, the balls always having to travel through a median line which is half the deflection angle of the joint in order to preserve constant velocity. The result is that, except for quite small deflection angles, because of this slippage and skidding of the balls, considerable heat is generated in the joint particularly at high speeds and high deflection angles. This drawback is avoided in the construction of the present invention. The present invention includes within its scope a motion transmitting device comprising a constant velocity speed changing drive coupling having a constant deflection angle between its input and its output and where the constant speed of the output is different from the constant speed of the input, said drive coupling consisting of a male and female element, said female element having a plurality of axial grooves on the internal part-spherical surface of said female element, said number of axial grooves being even, the same number of independently movable meshing elements, said number being divisible by four, said male element having a circumferential wavy groove disposed about the external surface of a part sphere of said male element, the number of said waves on said circumferential wavy groove being odd and either one more than or one less than said number of independently movable meshing elements, said meshing elements engaging in said axial grooves and said

CMPI

circumferential wavy groove simultaneously, thereby connecting said male and female elements, said male and female elements also being said input and output. Since one of the male and female elements constitutes the input and the other the output, this device is thus a low ratio torque converter in which the input and output are at a fixed angle to one another. It is readily possible, in practical embodiments, to make this angle to be any desired angle from say twenty degrees up to say forty degrees or more.

A motion transmitting device as described above thus forms a constantvelocity fixed angled joint which, as previously explained, is a high speed high torque joint of high efficiency.

If the low speed ratio of the joint is not acceptable then two such joints may be coupled back to back. The two devices may be similar having equal but opposite speed ratios so that the output speed of the assembly is equal to the input speed or alternatively the two devices may be arranged so that their speed ratios aremultiplied. Two devices so coupled may be arranged so that the output axis is parallel to the input axis or so that the angles between the input and output of each device are additively combined to give a required overall angle between the input to the first device and the output from the second.

Intermediate angles may be obtained by relative rotation of one joint with respect to the other about the axis of coupling between the two joints. As will be explained later, the length of this coupling may be made effectively zero by making the two joints concentric.

The inyention furthermore includes within its scope a motion transmitting device including

(a) meshing means in the form of a series of independently movable meshing elements whose centres are constrained to remain on the circumference of a swashing circle relative to a male and a female element,

(b) said male element being formed with a circumferential wavy groove, said groove being partially complementary to said meshing elements,

(c) a series of individual movement-limiting means, incorporated in a female element, whereby said meshing elements are caused to precess around said circumferential wavy groove in said male element, wherein said male and female elements rotate relative to each other at different speeds and at different intersecting axes, each of said individual movement-limiting means guiding in captive dependency always the same individual meshing element within specific limits of arcuate oscillating motion relative to said female element,

OMPI

said arcuate oscillating motion of the centres of said individual meshing elements being in three degrees of freedom of linear motion relative to said male element, one of said male and female elements being the input and the other the output.

The meshing elements conveniently are balls. In one preferred construction, said female element has a plurality n of predetermined stations evenly spaced on a plane at right angles to the axis of rotation of the female element, where n is an integral multiple of four, any number of or all of said stations being the site for an arcuate concave groove disposed radially about and on median lines of an internal surface of a part sphere, which grooves constitute said movement-limiting means and wherein said meshing elements are balls partly recessed in said arcuate concave grooves, said male element being in the form of a part-sphere incorporating said circumferential wavy groove, said balls constituting said meshing elements being partly recessed in said circumferential wavy groove, said male and female elements rotating differentially and at relatively inclined but inter¬ secting axes, the number of waves on said circumferential wavy groove being (n+1) or Ch-ll, whereby said balls are caused to precess around said circumferential wavy groove, thereby creating a predetermined fixed ratio for said differential rotation.

OMPI

In the devices described above, the torque conversion is achieved by the oscillating motion of the swash plate in the axial plane. The combination of features described above will be referred to hereinafter as an Axial Wave Drive unit. In specific examples, there is provided an input, an output and data means, one of which is a first shaft and another of which is a second shaft and the third of which is a frame, sa first and second shafts being separately relatively rotatable with respect to the fraπe about a ocmim axis. For this purpose, the exarrples have included a coupling, such as for exaπple, a ccnstant velocity universal joint as a device that brought the swashing rotating output back to the axis of the drive or, in the case where the swashing element is not rotating, the constant velocity universal joint is used to lock it to earth. With high deflection angles of constant velocity joints, such joints however become highly inefficient so that the efficiency of the axial wave drive unit in torque conversion is dissipated or partially dissipated by the provision of the constant velocity joint to bring the output drive back to the desired axis.

This problem can be overcome by the use of a second axial wave drive unitas the coupling to bring the output back to a desired output axis.

The present invention, thus further includes within its scope a motion-transmitting device comprising

a first and a second axial wave drive unit as described above, said second axial wave 'drive unit being arranged to bring the drive from the swashing element of the first axial wave drive unit to a rotatable output element. This rotatable output element may readily be made aligned with an input element to the first axial wave drive unit. The torque or speed changing ratio of the two axial wave drive units may be combined to give a higher ratio than the individual ratios or combined to give a lower ratio. Conveniently the two axial wave drive units, which each have male and female elements, are made concentric with the female element for the inner unit having meshing elements engaging a male element of the inner unit, the female element of the inner unit constituting the male of an outer unit and having separate meshing elements engaging in a female of the outer unit. In such a construction it is convenient to make the unit with the greater number of meshing elements the outer unit. In the two-stage arrangement, both stages can be simplex or both can be compound or one can be simplex and the other compound.

It is possible in any of the constructions described to use a plurality of wavy grooves, in which case some are asymmetric. Such an asymmetric wavy groove may be envisaged as a sine wave superimposed on a line of latitude of the earth away from the equator. ^" Because of the spherical nature of the earth the shape on the north side of the line of latitude must differ from the shape to the south. The peaks of the circumferential wavy grooves may be

O PI

machined away down the wave to the points where there is sufficient material to provide adequate strength between the flanks.

It will be appreciated that, with this two-stage construction, a wide range of speed ratios can be obtained by choice of the speed ratios for the individual stages by choice of addition (multiplication) or subtraction (division) of the speed ratios of the two stages.

Thus considered from another aspect the invention includes within its scope a motion-transmitting_ device comprising

(a) an input, an output and datum means, one of which is a first shaft, another of which is a second shaft and a third of which is a frame said first and second shafts being separately relatively rotatable with respect to the frame;

(b) a first axial wave drive unit having a male member and a female member, at least one of which members is angularly movable about orthogonal axes which are orthogonal to and intersecting said common axis at a common centre;

(c) one of said male and female members of said first axial wave drive unit being coupled to the first shaft by first coupling means and the other of said male and female members being either the frame or coupled to a second axial wave drive unit by second coupling means;

(d) the coupling means for the or each of said male and female members of the first axial wave drive unit including swashing means;

(e) a plurality of meshing elements between the male and female members, said meshing elements being located on one of said members by a circumferential guide having waves, the number of waves being (n - 1) or (n + 1) where

10 n is an integral multiple of four, and said meshing elements being constrained by the other of said members to be each at any or all of the respective ones of a plurality of locations?

(f) said locations (i) being points arcuately spaced

-. ς 360 degrees apart on a part-spherical surface around said cαπmαn ⁱ³ n centre, or (ii) being guides along arcs of median lines with a part-spherical surface about said common centre, which median lines pass through said points, or (iii) being wavy circumferential guides of the same wave 20 amplitude as the waves of said one member with the median lines of the waves passing through said points, each wavy circumferential guide extending around a part-spheroid of said other member, the number of waves around the circumference being (n + 1) or (n - 1) according as the number of waves on said one member is (n - l) or (n + 1) so as thereby to differ by two therefrom, whereby the meshing elements form a coupling between the male and female members causing one to precess relative to the 5 other with simultaneous relative swashing motion;

(g) the second axial wave drive unit being concentric with the first axial wave drive unit.

OM I

In the. following description, reference will be made to the accompanying drawings in which:-

Figure 1(a) and Kb) are schematic representations of grooves in a female stator and in a male rotor; Figure 2 is a diagram similar to parts of Figures 1(a) and 1(b) but illustrating, at 2CaF, a construction having a stator with eight grooves and a rotor with seven waves, at 2Cbl a stator with eight grooves and a rotor with nine waves and, at 2Ccl a stator with nine waves and a rotor with seven waves;

Figure 3 is a diagram showing a male swash plate and illustrating a co-operating female stator drawn in male configuration;

Figure 4 is a sectional view showing the general arrangement of one construction of torque converter; Figure 5 is a diagram illustrating grooves on part of another construction of male swashing element and female stator:

Figure 6 is a sectional elevation illustrating a torque converter where both the male rotor and female stator swash by the same degree But in opposite directions;

Figure 7 illustrates a drafting machine for generating the wave form used in circumferential wavy grooves such as are employed in embodiments of the invention? Figure 8 Illustrates a Ball cage " ich may be used in some embodiments of the invention;

O PI

Figure 9 illustrates a torque converter having spindles instead of balls as meshing elements;

Figure 10 illustrates another embodiment of torque converter; 5 Figure 11 is a explanatory diagram illustrating the provision of a plurality of wavy grooves;

Figure 12 is a diagram for explaining how the depth of opposing grooves in male and female members may be varied to reduce the differences in rolling velocities in the 10 two grooves;

Figures 13, 14, 15, 16 and 17 are diagrams illustrating different embodiments of motion transmitting couplings;

Figure 18 is a diagrammatic sectional view of yet another form of motion transmitting coupling. 15 Figures 19 to 24 illustrates further embodiments; and

Figure 25 is an explanatory diagram.

The simplest way to explain the invention is to compare the device with a large constant velocity universal joint. Such a constant velocity universal 20 joint has a male and a female element. Let us assume that the female element is the stator and that it has sixteen grooves in it with sixteen balls, one in each groove and let us assume that instead of sixteen grooves on the male element, a continuous groove is cut about the 25 circumference of the male element and that there are fifteen waves imposed on this groove of equal amplitude to the length of the axial grooves in the female element. This provision of a wavy groove with the number of waves άifferring from the number of balls is, or course, 30 quite different from the constructions employed in conventional constant velocity joints. If it were possible, and later in the text it will be shown that it is possible, for the sixteen balls to engage the fifteen waves in the groove of the male

- c. element, then, every time the male element was swashed through one revolution, the male element would rotate l/15th of a revolution.

As in a conventional constant v/elocity (CV) joint, the balls uill suash by half the angle of suash of the male element. If there is a cage for the balls, it too uill suash by this half angle. In order to get the male element to rotate, as described aboυε, the male element must be suashed by an angle uhich uill cause the balls at their maximum angle of suash to reach the peaks of the uaυes on the uaυe grooυe an the male element, so as to enter the next uaυe. Since the sixteen balls cannot precess in the grooves in the female stator and are trapped there, the bails have to precess relative to the male suashing rotor hy 1/I5th of a reυolutiαn for eυery input revolution of the drive shaft uhich causes the male element to suash. Thus a speed reduction or torque conversion of 15:1 is obtained. In Figure 1(a), the lines 1 show the fifteen waves on the rotor, the lines 2 represent the sixteen grooves on the stator, and the circles 3 represent the sixteen balls. Clearly, ignoring the cage in a CV joint, the internal surface of the female stator is the internal surface of a part sphere and also the external surface of the male rotor is the external surface of a part sphere.

In Figure 1(a), in order to show on a two dimensional surface that which is happening in a three-dimensional condition, the schematic representation is distorted in view of the necessary delineation of the lines in two planes. However,, this- delineation does not alter the proof. Thus- the zig-zag line 1 represents the wavy groove, with fifteen waves, which is cut on the rotor. The use of a zig-zag line with straight sections is a simplification which does not affect the basic explanation now to be given. The exact nature of the wave¬ form will be discussed later but in many preferred embodi¬ ments, it is a sinusoid on the surface of a sphere. The straight lines 2 represent the sixteen grooves in the stator. The circles 3 represent the sixteen Balls. The line 4 represents the median line of the balls —f lcfi is half the angle of swash of the angle of the grooves represented by the lines 2 . Point e , e* and \ξ represent the maximum points of the angle of swash of Both the male rotor and the balls in their cage. In other words e - f is the first 180° and f - e ^r is the next 180°. The spherical surfaces having been delineated in both planes, no ball has been shown at e' since it is in fact coincident with e when brought back to a sphere. From this schematic diagram, it becomes apparent that sixteen balls will mate with fifteen waves perfectly. The balls phase perfectly on the median line and each ball progresses along each wave and, as a result, prεcesses

.fPI

about the male rotor causing the rotor to rotate since the balls are trapped in the grooves of the female stator.

Figure 1(b) is a diagram, similar to Figure 1(a), but illustrating the condition where there are seventeen waves and sixteen grooves and balls. It will be seen that the intersections are on the opposite flanks compared with Figure 1(a) and thus the rotation would be reversed. In this arrangement, the ratio is 17:1.

So uith an odd number of uaυes , there is always an even number of balls that can intersect on the correct median line. The number of balls aluays is one more or one less than the number of uavεs. This is a very important teaching to uhich uε shall return later.

It is important to realise that there must aluays be an add number of uaves and an even number of balls. Careful examination of Figures. ^" 1(a) and l-(b) demon¬ strates this. Since each half of the suashiπg rotor is moving axially in the opposite direction to the other half at any instant in time, it must be arranged that the balls in each half react on the opposite flank of the uaves; otheruise one half set of balls uill be trying to precess about the rotor in the opposite direction to the other half.

By having an odd number of uaves and an even number of balls, it is possible to have each half set of balls acting an the opposite flank of the uave. Since each half o the suash plate is moving axially in the opposite direction to the other at any instant, this double reversal causes all of the balls to be pracεssing in the same direction around the rotor.

An important teaching is apparent from the ahove. As mentioned earlier, when the. number of balls is one less than the number of waves the reaction of the ball is on the opposite flank compared with the case when there is one more ball than there are waves. Thus the direction of rotation of the rotor is governed in accordance with which flank the Ball reacts.

Figures 2 aI-and 2 (hj are for explaining the effects of changing the numbers of grooves- in the stator and waves on the rotor. In Figure 2 al there is represented a stator with eight grooves and balls and a rotor with seven waves on the circumferential groove. Figure 2CbJ represents a stator with eight grooves and eight balls and a rotor with nine waves on the circumferen- tial groove on the rotor.

Figures 2 (a) and 2Cbl individually may be considered as representing simplex constructions. It will be seen that even though in one case there are seven waves and in the other nine waves, the positions of the eight balls are identical in each case. Because the positions are identical, the duplex or compound construction is possible. If now, instead of having eight grooves in the stator there is a circumferential groove on the stator, with seven waves on it and if, on the rotor, there is a circumferential groove with nine waves on it, from what has been shown above, the two elements can be connected by eight balls. This teaching is also of the utmost importance.

In the above described compound unit with seven and nine waves, as the rotor is swashed for every complete suash, the balls have to precess l/9th of a revolution relative to the stator. At the same time that this is going on ,the balls haυe had to precess l/7th of a revolution relative to the rotor, but in the opposite direction relative to the rotor since the balls are reacting on the same flank .of the respective uaυe to that on the stator, but travelling in the opposite direction. Clearly something has to give. The rotor turns to compensate for thε difference. This angular

1 1 9 + 7 1 difference in this case is r + ? = ~~~~~— ⁼ 3 ₀ 375' ° - revolution. Fig.2c is a delineated schematic drauing of this situation.

So uithout any increase uhatsoεvεr in the number of moving parts, thε speεd-chaπging ratio or torque multiplication factor can bε dramatically reduced, yet still retaining a

• large number of balls to transmit very large amounts of torque.

In conventional CV joints a cage is necessary to keep the balls on a true median line at all times. One of the problems is that,regardless αf the deflection angle of the joint, tuice eυery revolution, each groove in turn in the male and female elements become parallel and at this point form a perfect tunnel oouπ uhich the ball can roll. Should this happen, the joint uill jam at once. The cage prevents

OMPI

this happening. Also because of the violent axial shock loads imposed on CV joints, particularly in automotive applications on front wheel drive vehicles, it is important to have the cage keep the balls on a true median line at alltimes.

The simplex torque converter described above can be arranged so that the grooves in the female never become parallel with the wavy groove in the rotor. This is because the angle of the wave relative to the-grooves in the stator can always be made greater than the angle of swash. Similarly in a compound or duplex torque converter, it can be ensured that the grooves in the female are never parallel to the grooves in the male. So in the present torque converter, the cage could theoretically be dispensed with.

A major operating advantage of the torque converter over a CV joint is that the deflection (swash) angle is always constant and is known. Because of this the angle of swash of the cage and balls is also constant and known. It can be made half the angle of swash of the rotor. In view of this it becomes possible to positively swash the cage (if provided) as well as the rotor. This is very attractive since one no longer has to rely on the intersection points of the grooves on the stator and rotor to cause the balls and cage to

swash to keep the balls on the true median line at all times. This can now be done under totally controlled conditions and with great accuracy. In the compound configuration, where there is a wavy circumferential groove both on the stator and on the rotor, if it is desired positively to swash the cage, clearly the cage can no longer consist of a series of slots in which the balls are located, as in conventional CV joint practice and as in the simplex configuration with waves only on the rotor. Since the balls have to precess- relative to the stator, as well as relative to the rotor, and yet it is wished to positively swash the cage, the cage 'can be designed in the form of two circular guides parallel to each other, between which the Balls can precess and yet which can also be swashed and kept on a true median line. Later on, a description of a preferred form of the invention will explain how this can Be done. If it is not desired to swash the cage positively, this design need not be used and the cage can rotate with the balls.

It will now Be apparent, as was emphasised earlier, that the moving elements in this torque converter that are creating the torque multiplication are all moving in two planes and with three degrees of freedom of motion. These elements are the rotor, the balls and the cage.

Since the diameters of the working faces of the stator and the rotor are the same, ignoring the thickness of the cage, clearly the torque conversion is not being achieved radially, so herefore it is being created axially by the oscillating motion of the swash plate in the axial plane. This motion is converted into a radial component by the wavy groove in the rotor, and the degree of torque multiplication being a function of the number of waves, it is because of this that it is appropriate to call this system of torque conversion an "Axial Wave Drive".

The ratio of the device is determined entirely by the number of waves in the member having a wavy groove for a simplex construction or the numbers of waves in the two members for a duplex construction. The • direction of rotation of the output relative to the input depends on the choice of flank for ball residence as explained in the comparison of Figures 1(a) and Kb).

The steepness and depth of the waves in the circum¬ ferential groove is a function of the angle of swash and the ratio (i.e. number of waves) . Clearly the waves should not be too steep since this causes adjacent flanks of the wave to be too close to one another, particularly

at their apexes, thus resulting in insufficient material

between adjacent flanks, thereby causing weakness in the

structure. Also, the waves should not be too shallow

as this causes a very high "pressure angle" between

the flank of the wave and the flank of the groove in

the stator, the forces between the two passing through

the ball at that particular intersection. As will be

discussed later, in some cases the waveform may depart

from a sinusoidal waveform, so causing the wave flanks

to become steeper or flatter. This will be explained

in discussing how the waveforms are generated. It

is convenient however to discuss other features of

the device first.

Clearly the higher the ratio (more waves) the more

acute the wave angle. The lower the ratio (fewer waves)

the shallower the wave angle. In order to maintain a

steep enαigh wave angle to have an acceptable pressure angle, one

must increase the suash angle. Clearly there is a practical limit to the maximum angle of suash.

It is for these reasons that the deυicε in its simplex form is broadly limited to ratios from 7:1 to 20:1 per stage.

It can new be seen that it is possible *- obtain pure rolling motion betueen all the torque transmitting elements and that all the elements are in mesh all of the time and that in theory they are transmitting torque all of the time and thus getting the 360° embrace that uas desired. In practice, all the balls are not transmitting torque all of the time. Clearly, as a ball passes oυer the crest of a uaυe and is suitching from one flank to thε othεr, it is unrealistic to think that that ball is transmitting any mεaniπgful torquε , A further teaching which will be apparent is that, in addition to there always being an even number of balls, the number of balls must also be divisible by four. The reason for this is because of the inherent nature of the swash plate motion. Any point on the surface of the swash plate is moving in a three-dimensional path defined by two axes, the crucial point being that these two axes are at right angles to each other. Because of this, looking along the centre of the axis of the shaft that drives the swash plate, these two axes intersect each other at this central point. The outer ends of these two axes, i.e. at the outer edge of the swash plate rotor, are like the four points of a compass.

It is not enough therefore for there to be cnly an eυen number of balls. The number must also be divisible by four, because to those four points the balls must presεnt a fully symmetric condition and not a semi-symmεtrlc condition, uhich uould be the case if the number of balls uas even, but NOT divisible by four.

It has been convenient to refer to the number of balls as this simplifies the above explanation. It will be apparent however that one of the Balls could Be omitted without making the device inoperative. In principle, more than one ball could be omitted although the omission of balls does detract from the primary object of the invention, which is to utilise all the moving elements fully. Xn a simple? device, if a ball is omitted, the corresponding arcuate groove may also be omitted. The necessary condition more strictly is not that the number of balls is divisible by four but that the balls are appropriately located. In a simplex construction, the arcuate grooves have to be located on the spherical surface on lines of longitude spaced apart by n degrees where n is an integral multiple of four. Thus there may be n balls or fewer than n_ balls provided they are on appropriate lines of longitude. If these grooves are on the stator, the rotor must have (n - 1J _. or (n + 1) waves where n is an integral

multiple of four. As will be explained later, it is not essential to have grooves holding balls; fixed engaging elements or journalled spindles may be provided in a simplex construction. In this case, these elements must be spaced around the spherical surface at all or at only some of the points whose spacing is 360 degrees apart around the sphere their number only having to be even but not necessarily divisible by four. In a duplex or compound construction with grooves holding balls, the stator or the rotor must have (n - 1) waves and the other of these two elements must have (n ÷ 1) waves. The waves on each element must be of uniform pitch. For a compound construction, there may be n balls but, ^' as will be apparent from the following description, the device will still be operative if one or a few of the balls are omitted from their prescribed stations.

In Figures 1 and 2, it has been pointed out that the wave which shows as a zig-zag line has been distorted - because of its delineation In two planes.

The shape of the desired wave form for any given ratio is complex. A vital ingredient of the wave form is that at all times it shall be capable of providing three lines intersecting at the same point for each of the balls in the torque converter. These three intersecting lines are created by firstly, the swashing median line of the ball in their cage and secondly by the appropriate groove in the

stator and thirdly the corrεct point in the uaυy circum¬ ferential grooυε in thε rotor.

Thε rεlatiυe moυe εnt of any one of the oscillating balls and the suashiπg and rotating motion of the rotor, causes any αnε ball to trace the correct uaυe form on the surface of the rotor uhich is, of course, a part sphere. It is roughly similar to the sinusoidal uaυε form that an earth satellite's path traces oυer the surface of the earth, for eυery one complete reυolutiαπ of thε εarth. An important diffεrence, of course, is that earth satellites are launched in such a uay as not ^' to complete a whole number cf uaυεs for each rευolution of the earth. Clearly, uith the torque conυerter, it is υital that there be a uhole number of uaves. In preferred embodiments certain parameters are chosen so that the waveform is sinusoidal (that is to say a sine wave imposed upon a sphere) . The actual shape of the wave is of academic interest only in so far as the wave can be generated. Later in the text, a three dimensional drafting machine will be described which generates this waveform.

The input shaft swashes the swash plate rotor element by known means, and it may also swash the cage. The output can be taken from the swash plate rotor through a conventional CV joint or other convenient coupling.

It has been convenient to refer to a stator and a rotor. These are interchangeable in that in any given construction, either element may Be held stationary and the other made rotatable. In other words the stator can be the rotor and the rotor the stator. The wavy groove can be on the stator or the rotor or both. However it is preferable to have a wavy groove on the male element.

In conventional CV joints, as has already been stated, whilst an approximation to pure rolling motion can be achieved between the balls and the male and female elements, some degree of skidding will always occur. The reason for this is that whilst in theory there should be no skidding, this could only happen if the balls were very small.

Using balls or practical size causes a situation where the balls are rolling on one wall of the groove of the female element at a contact point in the groove

QVPI

which is significantly further out radially from the centre of swash of the device than the contact point of that same ball where it rolls on the wall of the groove of the male element which is significantly 5 radially further in.

Since the balls have to swash through half the angle of the swash of the CV joint in order to obtain constant velocity, the delineated distance that the ball rolls over the female's groove is greater than the 10 delineated distance that the ball rolls over the male's groove. So skidding of the balls must occur in some degree. The balls cannot be allowed to precess at their chosen rate as in a ball thrust bearing.

In the simplex configuration of the torque convεrtεr, -•^ if the uavy groove is placed on the male elemεπt, rather than on the female element, by judicious choice of the size of thε balls and thε profile of thε groove, the delinεatεd distancε of onε uavε on the male and thε contact -point of the ball in the groove can be made to εqual thε dεlinεated ° distancε of the groove in thε female at the contact point of the ball, evεn though the uave in the groove of the male at t contact point of the ball is radially further in than the equivalεnt point an the female. Thus true rolling motion ca be achieved and the skidding found in a CU joint eliminated.

In the case of the compound configur tion, by putting the larger number of waves on the female element and the smaller number of waves on the male element the same rolling distance equalisation is achieved and skidding of the balls is again prevented. This is because the wave flanks are more upright on the element with the larger number of waves and less upright on the element with the smaller number of waves. The less upright flanks on the male are longer than the more upright flanks on the female. It has been indicated earlier that the ratio of the coupling is limited by the maximum number of waves that one can impose on the circumferential groove. The reason is that the angle formed by adjacent flanks of the wave becomes too acute and at the peak of the wave there is too little material between the flanks and so the structure is weakened and no significant torque can be transmitted by the ball when it is located in the groove at this point.

In order to overcome the above problem and still obtain a high ratio per "stage with the simplex configuration, it is possible to machine away all the material between the flanks of the waves at their peaks back down the wave to a point where there is sufficient material to provide adequat strength between adjacent flanks. This solution means that the number of balls that are drivingly engaged is reduced, depending on how much material has been machined away; however, since it is a high ratio torque converter, there are a large number of balls, and a ccmpartively large number of balls will be drivingly engaged to transmit torque.

The fact that the peaks of the uaves have been machined auay still does not allou the balls any additional freedom since they are still trapped by the cage and the grooves in the female element. The material on the male element is only - machined auay radially iπuard to that point uhere the radially inuard portion of the balls uαuld be aπyuay, so no additional freedom is offered to the ball in this direction either.

It has been stated earlier that there is a practical limit to the magnitude of the angle of suash, particularly ■ _j _0 uhsrs lou ratios (few uaves) are required.

One uay of reducing this problem is to suash both the male and the fεmale ≤iemεπts by thε same degree of angle, but in opposite directions. This in effect doubles thε relative angle of swash betueεn thε male and female 15 elεments uithout any increase in the angle of suash relative to the input and output shafts. In this configuration, the cage ceases to suash relative to the input shaft and remains at right angles to it, since it has half thε εnglε of suash relative to the male and to the female elements. 20 The female suashing elεmεnt is locked to thε frame through a conventional CV coupling and the suashing malε element is tied to the output shaft through a conventional CV coupling.

In any multitooth (element) engagement torque 25 transmitting device, it is very important for there to be load sharing betueen the plurality of engaged elements. If this does not happen the uhole purpose of achieving multitooth

CMPI

eπgagement is negated and thε full torquε uill be transmitted by only onε or tuo of the engagεd elements and because there is no inherent load sharing capability and due to different tolerances introduced by machining errors, the remaining elemant that are designed to be taking their share of the torque uill bε doing πα uork uhatευer.

In this axial uaυe drive torque converter, load sharing is introduced, because in the first place the torque is transmitted betueeπ the male and female elements by separate balls uhich are free to take up their oun iπdiυidual positions at the intersection of the groαυes on the male and female elements. The cage, if provided, keeps the balls en a true median line, but the balls are located in slots in the cage uhich allou thε balls freedom of motion relatiυε to the cage in a circumferential sεπsε only, thus proυiding a sεlf indexing capability relatiυe to thε grαoυes.

It is also possible to accommodate and introduce a small degree of radial flcat capability in the suashing male elε ent to compensate for any υariatioπ in the tolerεπcεs in the machining of the dapth of the grooves.

So far we. have only considered a condition where the circumferential wavy groove has been generated by a point which is passing over the surface of the sphere at a point which is tangential at all times to a great circle of the sphere. This point is always moving tangentially at any instantaneous σnent that:it is generating the groove, regardless of what form the wave takes.

Therefore the circumferential wavy groove is symmetrically disposed on the spherical surface of the- swashing male element.

However, it is possible to dispose the circumferential wavy groove on a lesser circle of the sphere, in which case the circumferential wavy groove is asymmetrically disposed on the surface of the swashing male element. The wave form also becomes asymmetrical.

There are distinct advantagεs in being able to do this. It enables oπε to have a plurality of circumferential uaυy grooυεs on thε surface of the suashing malε εle ent. Each uaυy grocυe uill haυe the same number of uaves in it and each set of uaυεs uill bε circumferentially in phasε uith its axially disposed neighbour. The great adυaπtage is that , uith each additional circumferential uaυy grooυε,it becomes possible to have another set of balls transmitting, torque to the grooves in the femalε stator. Typically oπ _{e c} αuld have from tuo up to as many as fivε circumferential uavy grooves; the centre groove uould be generated on a great circle and be symmetric, the grooves each side of it being asymmetrical and generated on lesser circles.

In the example given earlier uith the simplex configurat uith fifteen uaves and sixteen balls, it uould nou be possible , if as many as five uaυy circumferential groαυεs uere provided on thε suashing male element, to have no less than eighty balls transmitting the torque betueεn thε male and female elements.

It is possible to apply this teaching to the compound configuration also. A plurality of grooves uhich are generated on lesser circles on the female and uhose uave form is asymmetric uill link up uith each set of balls in exactly the same uay as uas described earlier uith one uaυy circum¬ ferential groove in both the male and female elements. It is important that each matching pair of grooυes on the male and female elements be generated from a corresponding lesser circle so that each uavy grooυe uill haυe the same.degree of asymmetry in its uaυe form. The number of uaυεs must still be odd, being (n - 1) and ^" Cn + H where n is an integral multiple of four. The number of waves on the male and female elements must still differ by two. The number of balls (assuming the maximum number are used) must still be an even ^■ number n and will be divisible by four. It is the even number between the two odd numbers of the two wavy circumferential grooves.

Later in the text, it uill be described hou the drafting machine already referred to can bε adε to gεneratε the asymmetric circumferential uaυy grooυes on lesser circles of the sphere.

In these configurations it is still only necessary to haυe one cage, but It must be designed to accommodate as many sets of balls as there are sets of circumferential uaυy grooves. It may however, for ease of construction, be convenient to have one cage per set of balls.

_V arious preferred configurations of torque converter will now be described.

Fig. 3 shous a suash plate31 uhich is a portion of a sphere upon uhich is cut uavy circumferential groove32 upon its spherical surface. There are thirtεen uaves in the circum¬ ferential groove and it is emphasised that the uaυe form shouπ in Fig. 3 is only an approximation to the correct uave form. There are tuelve balls33 located in the uavy circumferεntial grooυε 32 uhich precess in it. A female stator34 is draun in the male cαπfiguraticπ in order to make it more under¬ standable to show the position of the balls 33 in ^" axial grooves 35 of the stator. In fact, the stator is a part of the surface of a spheroid with the grooves on its Internal surface. Dashed line 36 represents the swashing median line of the balls 33. This median line swashes at an angle h θ which is half the angle of swash of the swashing male member. This angle is shown at 37. The angle θ which is the angle of swash of the male element is shown at 38. The dotted lines 39 demonstrate that the balls 34 are in the same position both on the male and female elements.

Figure 4 is a general arrangement drawing of an axial wave drive torque converter In one of the preferred arrangements. An input shaft 41 Is supported In bearings In a frame 42 and is free to rotate In It. One end of the Input shaft 41 is bearingly supported by a spigot bearing 43 In an output shaft 44. A swash plate 45 is fixedly attached to the input shaft 41 and therefore rotates with it. An axial thrust bearing 46 imparts

Q PI

the. axial thrust of a swash, plate 45 to a swashing male member 47 through a thrust plate 48, which is fixedly attached to swashing male member 47. On the Internal diameter of swashing male memBer 47 is located and fixedly attached a conventional constant velocity universal joint which is shown as having male grooves 49 and female grooves 50 and Balls- 51. The male grooves 49 are cut in the male memBer 52 which is fixedly attached to the frame

42 through a radial plate 53. Thus the swashing male member 47 can only swash But cannot rotate since it is tied to the frame 42 through the constant velocity universal joint. There are twelve Balls 54 which are recessed in a wavy circumferential groove 55 in the swashing male member 47 and also are recessed In axial grooves 56 of a rotating female memBer 57 which is attached fixedly through another radial plate 58 to the output shaft 44. The female member 57 is split along the swashing line of the balls 54, as indicated at 57a, for convenience of assembly. A caσe 59 which swashes at half the angle of swash of swashing male member 47 has slots 60 In which are located the balls 54. The cage 59 keeps the balls 54 always on a true median line, whic median line is constantly swashing at half the angle of swash of the swashing male member.

The cage 59 rotates with female member 57, since the balls 54 are in slots 60 in the cage. The swashing male member 47 Is unable to move axially, except in a swashing sense, because the CV joint, shown in the drawing by male grooves 49, female grooves 50 and balls 51 is designed so as not to accommodate any "plunge".

OHPI

The swashing cage 59 is trapped between the spherical surface of the male jnember 47 and the female member 57 and so is incapable of axial motion other than in a swashing sense. The cage itself transmits no torque. Since clearly the swashing male element 47 is a torque reaction member, it is desirable to prevent any form of axial motion of this male element, except in a swashing sense and it will be noted that this element is prevented from any true axial motion because of the balls 54 acting in the grooves 56 and the circumferential wavy groove 55.

In this particular preferred embodiment, therefore, thε input shaft 41 rotates, so -rotating the suash plate 45, uhich, through the axial thrust bearing 46.transmits thε suashing action to the axial thrust plate 48 and thence to thε suashing male member 47 uhich suashεs but does not rotate, since it is tied to ths framε 42through thε male mεmber 52 by the CV ; coupling represented by ths grooves 4? and 50 and the balls 51 . Since the balls 54 are captured by the grooves 56 and the slots 60 in the cage 59, thε balls 54 are forced to precess in the uavy circumferential groove 55 causing the female element 57 to rotate, uhich transmits this rotation through the radial piste 53 tα the output shaft ^ at a reduced speed and multiplied torque relative to that proυided by the input shaft. Thε reduction of speed and thε multiplication of torque are a function of thε number of uaυes in the circumferential grαoυε 55 and thε number of balls 54 and grooυes 55 as previously described.

Figure 5 is a schematic drawing, In a flat plane, of 180 of an axial wave drive unit having 21 waves in the circumferential groove, of whic cnly 10% can be seen because cnly 180 is dram. For simplicity, the waves in this diagram are shewn as zig-zag lines. Ihe surfaces of the male swashing eleπent 62 aid he female stator element 61 have been delineated in both planes for reasons of clarity. Ωie lines 63 represent the centre lines of -tile axial grooves on the female stator elemsnt 61. The lines 64 represent the oentre line of the wavy cLrcumfe

¹⁰ tial groove on the male swashing element 62. The lines 65,intersecting the lines 64, show thereby the points at which the peaks of the waves have been machined away on the swashing male element ^" 6 ^" 2 because of the very acute angle of their peaks causing there to be Insufficient material at

~ this point between the flanks of the wave to be capable of providing useful torque. The line 66 represents the median line of the balls 67 as they swash in their cage at half the angle of swash of the swashing male element 62.

It will be seen that, since the peaks of the waves

20 have been machined away, the two balls (shown at 681 at .~. ^~ i end of the 180 are beyond the lines 64 and that the two axial grooves 69 at each end of the 180° do nc- intersect with the lines 64 any longer. However the balls 68 are still trapped in the grooves 63 and by the slc-s In the cage 25 and by the surface of the metal 70 on the swashing male elem 62.

OI.TI

This demonstrates the teaching described earlier that a compara ively high ratio per stage can be obtained with a modest angle of swash ar-ά have acute angled wave fronts and still have a large number of balls transmitting torque. In the example givenwhere a theoretical maximum of twenty halls should be trans¬ mitting torque, in act af er cutting away the wave peaks we are left with fourteen halls transmitting torque. In fact of the theoretical maximu _cf twenty balls, only eighteen would normally ^" be doing any useful work, since two of the halls are changing from one flank tc the other and at that moment are unable to transmit torque. So in practice with this configuration, the machining away of the peaks of the waves results only in that four more calls are not functioning.

Figure 6 shows a con iguration of an axial wave drive torque converter where both the male rotor and the female stator both swash by the same degree but in opposite directions, as has been described earlier. Stator member 71 is the female element of a con¬ ventional CV joint where no accommodation for "plunge" is provided for. For clarity, no cage is shown ir. this CV joint. The eirber 71, for asseirfoly, is split along the line 71a. Balls 72 roll in grooves in the female element 71 and in the grooves on the male surface of an element 73 in the conventional way. On the inner surface of element 73 are machined grooves which element woul

BAD ORIGINAL

normally represent the female stator in an axial wave drive. Element 73 is split alcng line 73a for purposes of asseπbly.

In this case the element 73 is swashed cj a swash plate 74 which is fixedly attached to an inpu shaf ^5. Swash plate 74 transmits its swashing drive through balls of an axial thrust bearing 76 against a radial face 77 of element 73. Since there is no "plunge" capability in the CV joint on stator 71, no axial movement except in a swashing sense is possible of element 73- A male swashing member 78 has a circumferentially wavy groove 79 machined on its outer surface. Balls 80 recess in this groove 79 3. .ά also recess in axial grooves 81 of element 73. Male swashing member 78 is swashed by- second swash plate 82 which has the same but rppcsite angle to swash plate 74. Swash plate 82 is also fixediy attached to input shaft 75. Swash plate 82 x-ansmits its swashing drive through balls of an axial τhruεt bearing 83 against a radial thrust face 84 to male swashing element 78. T e balls SO are held in slots in a cage So which is fixedly attached to stator elemen 71 ou radial spokes 8-5. Radial slots are cut in the element 73 to accommodate these radial spokes 55. 'Ihese slots are located between the axial grooves for balls 72 on the outer surface of element 73 and on the underside of each

CΪ.1PI

VVIPO

wave on the inner face of element 73. The spokes 85 alternate each side of the balls 30 so that the slots for the spokes do not cut into the wave form. Also enough radial width, is provided in the slots to provide for the inherent radial motion caused by the figure of eight effect mentioned earlier in a swash plate motion.

The reason the cage 86 can be fixedly attached to stator element 71 through spokes 55 and does not need to swash through half the angle of swash of the. ale swashing element as in previous configurations, is because the male and female elements are both swashing by the same angle but in opposite directions.

The male swashing element 78, en its inner surface, has a conventional CV joint which again is designed not to accommodate "plunge" so that there can be no axial motion, except in a swashing sense, of element 78. Balls 37 transmit the rotational torque of element 78 caused by the circumferential wavy groove 79 from the female axial grooves 88 to male axial grooves 89 on a male element 90 of this CV joint. This male element 90 is integral with an output shaft 1. For clarity no cage is shown in this CV oint.

The input shaft 75 is suppor ed in the output shaft 91 by a needle s igot bearing 92.

run ORIGINAL

'PI

¥ith this configuration, because of the double swash of both the male and female elements, the apparent angle of swash between the two elements has ^' beer, doubled, even though the angle of swash of these elements relative to the input shaft and the output shaft has not been increased. This construction allows one to have a very ew number of waves in the circumferential groove and thus get a low ratio and- yet still have an acceptable pressure angle on the flank of the wave. If only the male element were swashed in the conventional way, the angle of swash would have to be so. great that it would be impossible to get a large enough diameter on the output shaft from the CV joint to. take the torque generated by the axial wave drive. Wher-e there is a compound configuration and where the cage is not free to rotate since it is desired positively to swash it, as for example in the construction of Eigure 6, and if this Figure 6 construction was arranged as a compound axial wave drive rather than the simplex configuration that has just been described, then clearly the balls 80 would have to be able to rotateabout the axis of the cage since they would precess relative to element 73 and swashing male element would also be rotating in the opposite direction. In order to accommodate the rotation of the balls 80

OMPI ^"

about the axis of the whole device, it is necessary for there to be a continuous circumferential slot in cage 86. This can be achieved by making the cage in the form of two rings supported respectively by two sets of spokes 85- These two sets of spokes are located one on each side of the balls 80 and are accommodated in radial slots through the element 73 as already described.

A three dimensional drafting machine that generates the wave form on the circumferential wavy gr oves will now be described with reference to Figure 7. This

Figure is a general arrangement drawing of the device. A base frame 101 through a bracket supports 102 carries a drive tube 103 which is free to run in the bracket supports 102. A radial arm 104 is fixedly attached to the drive tube 103, as is also a cranked radial arm 105. A notched belt pulley 106 is fixedly attached to the drive tube 103. The notched belt pulley 106 drives, through a notched belt 107, another notched pulle;/ 108 of the same diameter as notched pulley 105. The notched pulley 108 is fixedly attached to a lc-.-;er drive shaft 109. Thus, when drive tube 103 is rotated, the lo^-rer drive shaft 109 rotates at the same speed and in the same direc-ion. Another notched pulley 110 is fixedly attached tc the support bracket 102 ar-d thus ~o the case frame 107 and thus cannot rotate. Z e pulley 110 is

BAD ORIGINAL

connected through another notched belt 111 to a further notched pulley 112 on a gyrating shaft 113. The gyrating shaft 113 is free to rotate in the radial arm 104 and is fixedly attached to the notched pulle;/ 112. The notched pulley 112 and notched pulley 110 are of the same diameter.

As gyrating shaft 113 is gyrated it is unable to rotate because of the 1:1 ratio of the notched belt 111 and pulley 112 and 110 combination and the fact that the notched pulley 110 is tied to the base frame 101.

Gyrating the gyrating shaft 113 does however cause the drive tube 103, the radial arm 104, the cranked radial arm 105 ana the lower drive shaft 109 all to rotate at the same speed and in the same direction. The gyrating shaft 113 has a further no ^~ ched pulley 114 fixedly attached to it, which drives, through notched belt 116, another notched pulley 115, which is fixedly attached to one end of an upper drive shaft 117, which is-free to run in drive tube 103. At the other end of the upper drive shaft 117 is fixedly attached another notched pulley 118 which, through a r.oτ.ched belt 119, drives a shaft 121 through notched pulley 120 which is fixedly attached to shaft 121. The ratio between the upper drive shaft 117 and the shaft 121 is 1:1 since the two notched pulleys 118 and 120 are of equal diametei

BAD ORIGINAL

Provision is made for changing the size and therefore the relative ratio between the notched pulleys 114 and 115, so that,as the gyrating shaft 113 is gyrated, it can cause the upper drive shaft 117 to rotate at a totally different speed from that of the drive tube 103. A plain pulley 146 is a tensioning pulley to keep the notched belt 116 taut when the sizes of the notched pulleys 114 and 115 are changed.

The shaft 121 is connected to a CV coupling 122. A shaft 123 emerges from the other side of this CV coupling 122 at a considerable angle of declination to shaft 121 - typically 35°. This angle of declination is kept constant. The shaft 123 connects to a second CV coupling 124. The other end of second CV coupling 124. connects to a cylinder 125 which passes back over CV coupling 124 and shaft 123- One end of a bearing arm126 supports a journal bearing 127 in which the cylinder 125 is rotatably supported. The other end of the bearing arm 126 is bolted in an arcuate slot 128 which is cut into the cranked radial arm 105.

The whole cylinder assembly and bearing arm can pivot about a pivot centre 129 which is the centre of the CV coupling 124. The pivot centre 129 is located o the centre line of- the upper drive shaft 117. By releasing a locking nut 143 on the bearing arm 125 and allowing the

BAD ORIGINAL

bolt carrying arm 126 to slide in the arcuate slot 128, the nut 143 enables the arm 126 to be bolted at whatever angle is desired. A cellar 130 is fixedly attached to the cylinder 125- This collar 150 holds an opaque glass sphere 131.

If the notched pulley 114 has thirty teeth and the notched pulley 115 has twenty-eight teeth, the movement of the gyrating shaft 113 through one complete gyratory revolution will have caused the upper drive shaft 117 to revolve l/l5th of a revolution.. At the same time the drive tube 103 will have made one revolution.

The upper drive shaft 117 ultimately turns the opaque glass sphere also through l/l5th of a revolution - but at an angle of declination provided by the two CV joints 122, 124 and the position en the arcuate slot 128 where bearing arm 126 has been bolted. However, since the arcuate slot 128 is attached to the cranked radial arm 105 which is attached to drive tube 103, the cylinder 125 will be made to swash by the bearing arm 126 once for every gyration of the gyrating shaft 113 and at the same time swashing the opaque glass sphere 131. This opaque glass sphere 131 will rotate l/lrτh of a revolution at the same time.

It has already been indica ed that the lower drive shaft 109 rotates at the same sreed as τhe drive τube 103.

BAD ORIGINAL

The lower drive shaft 109, which is bearingly mounted, at each of its ends, in the base frame 101, has fixedly attached to it a crank member 132, whose angle of incidence can be adjusted relative to lower drive shaft 109 by a bearing arm 133 ±n. an arcuate slot 134 in arm 145 attached to shaft 109 and locked by nut and bolt 135. The crank member 132 pivots about a bearing pin 144, which, at the instantaneous moment as drawn, just happens to be coincident with pins 137. A fork 136 can pivot on the pins 137 which are attached to a bearing sleeve 138 which can rotate relative to the crank member 132.

The fork 136 is attached to a vertical shaft 139 which passes through a bearing 140 in the base frame 101. The shaft 139 is adjustably attached to ^' a stylus arm 141 by a locking nut 143. The stylus arm 1^1 can be adjusted radially on shaft 139 by loosening the locking nut 143. In Figure 7, the stylus arm 141 is shown displaced y 90° of arc from its normal mia-pcint position. This has been done for the sake of clarity, in order to show the shape and position of the stylus arm 141. A stylus 142 is located at the upper end of the stylus arm 141 at a point which is exactly on the same horizontal plane as the axis of upper drive shaft 117.

The axis of vertical shaft- 139 is at right angles to the axis of u-coer drive shaft 117 but in the same vertical

BAD ORIGINAL

plane as the axis of shaft 113. The axis of vertical shaft 139 also passes through the pivot centre 129. The stylus arm 141 is suitably shaped to curve round the opaque glass sphere 151, so that the stylus 142 may rest correctly on the surface of opaque glass sphere 131 on exactly the same horizontal plane as the horizontal plane of the axis of upper drive shaft 117.

For each complete gyration of gyrating shaft 113, the lower drive shaft 109 rotates once. This causes the stylus arm 141 to oscillate about the axis of the vertical shaft 139. The number of degrees of arc through which it oscillates is directly proportional to the angle at which the crank member 132 is set relative to the lower drive shaft 109 by the adjusting of the locked position with nut and bolt 135. So, as the opaque glass sphere 131 oss one full cycle of swash and also rotates l/l5th of a revolution, the stylus 142 will also have acne one complete oscillation.

It will become apparent now that the stylus 142 is duplicating the motion of the oscillating balls in the grooves of the female stator element of an axial wave drive unit and the opaque glass sphere 131 is duplicating the swashing and rotating motion of z e male element in an axial wave drive unit. Since the angle of swash of the balls and the cage en their swashing median line, in the embodiments so far described, is

half the angle of swash of the swashing male element, the angle at which the crank member 132 is set at half that at which the cylinder 125 is set.

It can be seen that, by adjusting the ratio of notched pulleys 114 and 115, the speed of the upper drive shaft 117 relative tc the drive tube 103 can be altered in order tc get whatever number of waves is required, on swashing opaque glass sphere 131, relative to one whole revolution. The depth of the wave and- hence the angle of swash can be chosen by adjusting the angles of the cylinder 125 and the crank member 132. Thus, almost any combination and number and form of circumferential wavy linescan be generated by the dra ting machine to duplicate the path of the desired circum erential wavy groove.

Normally, in order to generate a line representing a symmetric circum erential wavy groove where the generating point is the tangent to a great circle at all times, the stylus arm 1£1 is locked to ^' the vertical shaft 139 by the locking nut 143 in a position such tha , when the stylus arm 141 is in a position where its radial arm is at right angles to the axis of the upper drive shaft 117, after one full gyration of gyrating shaft

113, the stylus am 141 will oscillate by an equal number of degrees of arc each side of this position.

If asymmetric circumferential wavy lines are to be reproduced, then by loosening the locking nut 143, the stylus arm 141 can be moved by the degree of asymmetry desired away from this centre point and locked again.

BAD ORIGINAL

^OMPI

The above described drafting machine generates the required waveforms. It enables one readily to see the effect on the waveform of changes in various parameters. When analysing the waveform of the circumferential wavy groove in any particular configuration of an Axial Wave Drive unit, it is important to understand the path that a point on the surface of a swashing but not rotating sphere takes relative to a stationary stylus point.

For a given angle of swash this path will vary from that of a circle, if the stylus point is coincident with the axis of the input shaft driving the swashing element to that of a very elongated figure of eight as shown at 701 in Figure 25 when the stylus point is at right angles to the axis of the input shaft and if the point were extended, would pass through the centre point of the swashing sphere. Generally, in the present torque con¬ verters, we are concerned with the elongated figure of eight. In the position where the generating point is at right angles to the input shaft where it can generate a symmetric waveform on the swashing and rotating sphere, as has already been indicated, if the sphere is not allowed to rotate, the path generated will be that of an elongated figure of eight. The length of the figure of eight will

be a function of the angle of swash.

A very important teaching now emerges. If the stylus is oscillated in an arc whose radius is equal to the radius of the sphere, and the centre of the circle of said arc intersects the axis of the input shaft and the plane of oscillation is in line with the axis, of the input shaft and furthermore that the oscillation is in phase with but is half the amplitude of the angle of swash of the sphere, then the path that the stylus generates will become a straight line 702 drawn within the figure of eight in Figure 25. Such a straight line, of the appropriate amplitude, is shown at 702 on the left of the Figure, the line being drawn within the corresponding figure of eight curve 706. The reason for the halving of amplitude is because the two motions are in phase with each other and therefore the deflection angles subtract from each other. This trace in effect is duplicating the motion of the balls in the arcuate grooves in the female stator. Since the amplitude is halved, therefore, for a given height, the angle of swash has to be doubled to get the straight 702 to be amplitude of the sine wave 703 and therefore the figure of eight would be double the amplitude, as is shown at the left of Figure 25.

Clearly therefore in the above condition just described, since a straight line is produced when the sphere is swashing but not rotating, as soon as it is

arranged for it to rotate at a predetermined speed, the path generated by the oscillating stylus will be that of a sine wave imposed upon a sphere as shown by curve 703 in Figure 25. This is the preferred condition and the preferred waveform for the Axial Wave Drive unit. For a simplex or a duplex unit, this is achieved by making the angle of swash of the balls half that of the relative swash angle between the male and female elements. One configuration previously described dispenses with the oscillating balls and arcuate grooves in the female stator and substitute radially disposed spindles which is the equivalent to having a stationary stylus point. In which case, each half cycle of the elongated figure of eight 701 is imposed on the waveform and a significantly modified sine wave is imposed upon the swashing and rotating sphere. Depending on the relative directions of rotation the effect is either to steepen the flanks as shown by dashed line 704 in the left of Figure 25 or to flatten them as shown by chain lines 705 in the right of Figure 25.

However, there is no reason why the ratio of 2 : 1 between angle of swash and angle of oscillation need not be changed, but the waveform ceases to be a sine wave imposed on a sphere. The angle of oscillation and

OMPI

therefore the angle of swash of the median line of the balls can be infinitely varied relative to the angle of swash of the sphere and can be a useful design tool where it is desired to reduce the deflection angle of an angle drive unit, yet maintain, a good wave height.

It is also a useful design tool in obtaining equality of rolling velocities of the balls on the surface of the walls of the grooves in the male and female elements by apportioning the rolling distance, caused by the ability to choose the angle of swash of the median line of the balls. The shape of the wave front can also be tailored to suit specific designs and configurations. The drafting machine can. be adjusted to duplicate the required conditions. Except where the 2:1 swash angle ratio is being generated, it is important to establish the direction of rotation of the sphere relative to the input shaft of the drafting machine, depending on if a waveform which will produce reversal or not is required. Contra rotation or not of the drafting machine is achieved by the correct choice of the ratios of pulleys 114 and 115 in Figure 7. Depending on the ratio of the deflection angles to each other, an infinite variation in waveform caused by the figure of eight effect can be obtained. The drafting machine can conveniently be used to

establish the path of a. point on the swashing sphere by adjusting the pulleys 114 and 115 to get unity ratio, so that the sphere only swashes and does not rotate. The stylus swashing mechanism can also be disconnected to create traces in a 90 arc.

In describing embodiments of this invention, mention has been made of a cage for balls located between the male and female members of the torque converter. Figure 8 shows a cage for balls 151, the cage ^* aving twin parallel circumferential rails 152 which are held in correct axial displacement to one another by several separate bridging elements 153 which pass well above or well below the paths of the preceεsing balls 151. The bridging elements 153 are accommodated by wide slots in the female stator element, these slots being spaced between the axial grooves in the female stator element. In the compound configuration the bridging elements actually pass through tunnels going ever the circum¬ ferential wavy groove in the female stator element, or under the circumferential wavy groove in the swash plate. By this arrangement the balls can precess relative to the cage and the cage need not rotate.

In order to make it possible tc assemble an axial --rave drive ni~, he female stater must be built up in two parts. The two parts interface at the median line of the alls in ^~ e cage. To assemble, the cage is put

BAD ORIGIN

OMPI

over the male rotor, assuming it has the circumferential wavy groove. The balls are placed in the slots in the cage and recessed correctly in the wavy groove. Then the twc female elements of the stator, whose interface has been machined to the angle of the median line of the balls in the cage, are placed around the male stator and the cage and balls and then bolted together. If the interface of the two elements of the female stator is positioned anywhere else, it will become virtually impossible to assemble.

The machinery of the waveform of the ball track on the rotor and/or stator in any of the configurations described can be executed from the locus of this track as produced by the drafting machine. A computer-controlled milling machine, with geared dividing head and fixtures can be used for this purpose. Alternatively, a three-dimensional pantograph with similar equipment can equally well be used. The latter method, although slower, can be useful for experimental purposes.

OMPI _

Where there are a plurality of circumferential wayy grooves on the swashing male rotor, then the female stator will have to be sliced into as many parts as there are median lines of balls plus one, to make assembly possible.

A further variation of the axial wave drive system, which can be used in any simplex configur tion, is to replace the owcillating balls and grooves in the female stator by needle roller bearing mounted radial spindles with the protruding part of each spindle pointing radially inwards from the female stator in the circumferential wavy groove of the male swashing rotor. In this case no cage is required. For ease of construction, the wave groove is formed in the male member and the spindles are bearingly supported in the female but the converse arrangement could be employed.

In order to generate the waveform with the drafting machine when using the spindle configuration, the only modification required is to stop the stylus from oscillating.

The schematic configuration for the spindle arrangement would be as in Figure 2 where the circles would represent spindles that are fixedly mounted on needle roller bearings facing radially inwards on the female stator instead of those circles representing oscillating balls in grooves in the female stator.

The same rules apply however, that the number of waves must be odd and the number of spindles must be one more or one less than the number of waves. The spindles must be located at positions which are evenly spaced around a circle at angular intervals of 560 degrees n where n is even numbered but in this configuration, does not have to be an integral multiple of four. There would normally be n« spindles, that is one at each location but, as previously explained the device would be operative if one or a few of the spindles were omitted.

In this configuration the female stator need no longer present the internal surface of a sphere. All the female stator has to be is a rigid circular frame on which the radial srindles are mounted. A further attraction to this configuration is that the angle of swash of the swashing male rctor is halved since the meshing elements are now stationary.

Figure 9 is a drawing showing one embodiment of such an axial wave drive con iguration with fixed meshing elements. A female stater 161 holds srindles 166 in

BAD ORIGINAL

-6€-

needle bearings 167. A swashing male rotor 162 has circumferential wavy groove 173 in which the spindles

166 mesh. An input shaft 163 rotates a swash plate

164 which is fixedly attached to the shaft 163. An axial thrust race 168, through the swash plate 164, swashes the swashing male rotor 162. An output shaft

165 is driven from the male swashing rotor 152 through a CV joint represented by a cage 169, balls 170, axial grooves 172 on output shaft 165 and axial grooves 171 on the male swashing rotor 162.

Since the CV joint 169, 170 has no accommodation for "plunge", the male swashing rotor 162 cannct be axially displaced, except in a swashing sense by swash plate 164. In order to introduce load sharing into this configuration, the distance between the end of each needle bearing 167 which supports a spindle 156 and the point where the spindle 166 meets the circumferential groove 173 can be increased (more or less cantilever in other words) and the shaft of the spindle 166 made a little elastic so that controlled deflection can take place, thus sharing the load between all the spindles.

It will be noted that, in this construction, unlike the construction of the previous mentioned ϋ.S-. Patent 2559093, there are spindles supported in needle bearings

167 to permit of rolling motion. Furthermore , there is no ball cage acting as a torque transmitting element. The cage 169 acts only as a guide member, this ensuring pure rolling motion and high efficiency.

OMPI

Figure 10 shows a general arrangement of an axial wave drive unit which includes means for positively swashing the cage at half the angle of swash of the male swashing element. However, in this particular configuration the female element with the axial grooves in this instance happens to be the rotating output and, for reasons previously explained in the description of Figure 4, the cage will have to be altered somewhat from that shown in Figure 8. In Figure 10 a female element 181, split at 181a for assembly, has axial grooves 182 and constitutes the rotating output.

A cage 183 for holding balls 198 is between the female element 181 and male element 186. It is preferable not to have bridges in the cage holding the two circular rails correctly axially disposed the one from the ether. Instead there are two sets of radial spokes 184, each set of spokes typically having either three or five spokes. Each set of spokes 184 is connected to one half of a circumferential circular rail of the cage 133. Ξ-ach set of spokes 184 passes through its respective

BAD ORIGINAL

set of slots 185 in the swashing male element 186. The spokes 184 pass on through other slots 187 between the axial grooves 188 in a CV joint 189. These spokes 184 also pass between axial grooves 190 in the female element of the CV joint 189 which is part of a swashing hub 191 which runs free through a needle bearing 192 on an angled crank 193 on an input shaft 194. The angle ₇ 0 of the angled crank 193 to the axis of the input shaft 194 is half the angle (β) of swash of the swashing male element 186. This male element has circumferential wavy grooves 195.

It will become apparent that the reason for the two sets of spokes 184 in this configuration rather than the use of bridges to connect the rails of the cage 183 is that the slots 185 cannot be passed axially all the way through swashing male element 186, since these slots would cut through the circumferential wavy groove 195- By this arrangement each set of spokes 184 is staggered radially so that a slot can be cut axially under each wave but not through the groove. The two sets of spokes 184, apart from being radially staggered are also offset axially, the one set from the other, by an amount rather more than the thickness of the circumferential wavy groove 195. In. this way sufficient strength is preserved in the swashing male element 136. Additionally a radial

BAD ORIGINAL f OMPI

thrust plate 196 can be bolted onto the swashing male element 186 and over the slots 185 after the spokes 184 have been installed. Also a similar radial plate 197 can be bolted on the other side of swashing male element 186 after the other set of spokes 184 have been installed.

•It can now be seen that the cage 183 c n new be positively swashed, the balls 198 thereby swashing and being kept on a true median line at all times even though the balls 198 are also precessing relative to the swashing male element 186 and orbiting around the cage 183 at the same time.

Figure II illustrates a configuration where there are two asymmetric circumferential wavy grooves disposed on lesser circles of swashing male element which is a part sphere. In this Figure, there are shewn diagrammatically a male element 201 constituting a rotor and a female element 202 which is the stator. There are seven waves in each circumferential wavy groove 205 on the male element 201 and there are twe sets of eight balls 204 which are partly recessed in these circumferential wavy grooves 205 and are also partly recessed in eight axial concave arcuate grooves 206 disposed around the female stator 2 2. cage 203 holds the balls 204 in two sets of slots circumferentially

BAD ORIGINAL

disposed about the cage 203. Dotted lines 207 represent the two swashing lesser circles on which the cage 203 causes the balls 204 to track.

The angle θ is the angle of swash of the swashing male element 201 and the angle _t 6 is the angle of swash of the swashing cage 203, this being half the angle of swash of the swashing male element 201.

It is emphasised that the form of the circumferential asymetric wavy grooves in Figure 11 is only an approximation to their true form. This Figure shows how it is readily possible to provide a plurality of circumferential wavy grooves whilst still keeping the device to a small size. The increased number of balls results in a corresponding increase in the torque handling capacity.

Earlier, it has been described how the skidding of the balls can be prevented, in the simplex construction, by having the circumferential wavy groove on the swashing male member and the arcuate grooves on the female member and, in the duplex (compound] configuration, by putting the smaller number of waves on the swashing male member and the larger number of waves on the female member. However, whilst the total delineated distance for each swash that the balls cover on the male groove and the female groove respectively can be

equalised in this manner, it is only the total distances. At certain instantaneous moments the velocities over the surface of the respective grooves on which a particular ball is travelling will not always be equal. This occurs because the flanks of the waves on the swashing male member are not always on the same median line, whereas the arcuate grooves on the female element are. In order to compensate for this, the depth at which the ball contacts the walls of the circumferential wavy groove in the male member and the depth at which the balls contact the walls of the circumferential groove in the female member can be varied. The balls can thus be made to rise in one groove and fall in the opposing groove at any point in each swashing cycle. Thus, whilst in the symmetric configuration, the balls still stay at any instantaneous moment on a median line, they are continually moving radially in and out from the geometric swash centre of the swashing male member, which is a part-sphere and also radially in and out from the centre point of the female member, which is a part- spheroid. The thickness of the cage wall is sufficient to keep the balls in their grooves swashing in a true median line. Thus by varying the cross-sectional profile of the grooves, the balls can be made to rise and f ll in the grooves, thereby varying their instantaneous precession rate. This is illustrated in Figure 12 which

shows three examples of the condition just described. In this figure, a swashing male member 301 is inside a female stator 302 with cages 303 between them with slots 304 for balls 305. The groove on the left in the female member in the figure is shallower than the opposing groove in the male member. The contact point in the female groove is shown at 306 which is at a shallower depth than the contact point in the male groove shown at 307. In the centre of Figure 12, the conditions are reversed, there being a deeper groove in the female member, where the contact point is at 308, this being deeper than the contact point 309 in the groove in the male member. At the right hand side of the figure, the contact points 310 and 311 in the female and male member groove are at about equal depths. It should be noted that the thickness of the cages 303 is sufficient that, even though the balls rise and fall in the grooves, they still present a full diameter across the slots 304 in the cage. Thus the cage can still keep the balls swashing on the true median line. The lines

312 in Figure 12 are the diametric lines along which the opposing reaction forces act through the balls from the flank of the groove on the female stator to the flank of the groove on the swashing male member. xt will be noted that each of the motion trans¬ mitting devices described has a frame with two shafts.

O PI

Any one of these three members may be fixed and the other two members may then constitute the input and the output. The mechanisms are reversible so that step-up or step- down speed ratios may be obtained. Figures 13, 14, 15, 16 and 17 are diagrams illustrating different embodiments of angled motion transmitting couplings. Referring to Figure 13, there is shown a coupling having a female stator with eight axial grooves and a male element with nine waves. Stator bearings 401 carry an input shaft 402 driving a female element 404. An output shaft 403 is supported in stator bearing 409 such that the input and output shaft axes are non- parallel, intersecting at an angle. The female element 404 has eight axial grooves 405. A male element 406 on the output shaft 403 has a circumferential groove 407 with nine waves. Eight balls 408 engage in the axial grooves 405 and wavy groove 407. The wavy grooves and co-operating axial grooves are similar to those of previously described embodiments. For example, the material at the peaks of the waves of the wavy grooves may be removed to a predetermined distance radially inwardly. The coupling

is designed with the wavy groove on the male element and axial grooves of the female element to equate the surface distances that the balls are in rolling contact with the male and female elements shilst still maintaining their required path. Also, as previously described, the cross-sections of the grooves in the male and female elements can be arranged to cause the balls to rise and fall in the grooves, thereby enabling the instantaneous rolling velocities to be equalised. It is thus possible to obtain pure rolling motion and hence high efficiency.

In practice however, it has been found that, by appropriate selection of the radii of the swashing spherical surfaces and of the ratio of the swash angle of the median path of the balls to the relative swash angle of the male and female elements, ane by cropping the crests of the waves, it becomes unnecessary to vary the cross-section of the grooves.

The balls are caused to precess in what may be described as a swashing motion in a plane bisecting the angle between the axes of the input and output shafts. As previously explained, depending on whether the input is the male or the female element, the speed difference between the output and the input is either -Q- or _Tj - of the input speed.

P

A cage may be provided to constrain the balls to remain in this plane and such a cage may be positively restrained on its swashing plane relative to the male and female elements by separate controlling means. 5 However such a cage and cage drive are not essential . because the balls are constrained by the axial and wavy grooves to remain in this plane.

Although the embodiment of Figure13 has been described as having eight balls, it will operate if one 10 or more balls are missing. The corresponding axial groove may also be omitted. It is obviously preferable to have all .the balls present in order to obtain maximum power transmission and thus to have a smaller assembly for a given power rating.

- ¹ - ⁵ Although the joint of Figure 13 has been described using the female element as the input and the male element as the output, the device is reversible and thus the input and output can be interchanged.

A whole range of predetermined angled joints may ^ώW be made, these angles being a function of the depth of the waves on the circumferential wavy groove and the number of waves (ratio) . Exactly the same may be achieved with the compound configuration that has been previously described.

- PREA

Two constant velocity joints, such as are shown in Figure 13 may be coupled together to form a torque transmitting assembly. Figure 14 shows one such construction using two joints of equal ratio connected back to back on an angled interconnecting shaft. In this figure an input bearing 421 supports an input shaft 422 carrying a female element 424. This co-operates with a male element 423 on an angled interconnecting shaft 428 carrying a male element 426' co-operating with a female element 424' on an output shaft 427 carried in an output bearing 429. The input and output shafts 422,427 are parallel. The joints are of equal ratio but back to back so that the rotational speeds of the input and output shafts are parallel.

Figure 15 shows two joints connected so that their respective ratios are added to each other to increase the difference in speeds of the input and output shafts. An input bearing 431 carries an input shaft 432 and an output bearing 439 carries an output shaft433. The first joint has a female element 434 connected to the input shaft 432 and a male element436, connected by an angled connector shaft 438 to the female element 434' of the second joint. A male element 436* of the second element is connected to the output shaft 433.

It is not necessary to have any cage for the balls in the above-described joints because the wave angle of the circumferential wavy groove can be mace greater than the deflection angle of the joint. ^{In th±s wa} y the groove on the female and the groove on the malewave never become parallel at any point in the rotational cycle and thus never form a tunnel down which the balls could roll, which would cause the joint to lock solid. In the event that it is preferred to retain a cage for the balls, since the deflection angle of the cage is always half the deflection angle of the shaft and the deflection angle of the joint is constant, it becomes very simple to positively control the deflection angle of the cage without having to rely on the intersection points of the axial grooves in the female element and the' circumferential wavy groove in the male element.

Since one side on the outer surface of the cage will not be covered by the female element at the external angle of the joint, by simply incorporating a circumferenti groove at the side and on the external surface of the cage, a stator guide with a roller attached to it can turn in this groove and keep the deflection angle of the cage constant.

Depending on which shaft is driven, the male or the female, the output ratio will always be either l ^" plus a fraction or 1 minus a fraction. The magnitude of this fraction depends on the number of grooves and the number of waves in the wavy groove.

The rotational speeds of the male and female elements differ and, since the fraction is expressed as a fraction of the input speed, the numerical value of the fraction depends on which element is designated as the input. For example, where the female stator had eight axial grooves on it, there were eight balls and nine waves qn the male element, and a ratio of 9:1 is obtained, then in the coupling configuration, depending on whether the male or the female is the driven input, the speed difference between the input and output is either rr or -g- of the input speed.

C:.:PI

Figure 16 shows one example of the above configuration. Support bearing 441 carry an input shaft 442. An output shaft 443 is supported in bearing 441'. The joint has a female element 444 and a male element 445 with balls in a cage446. A circumferential groove 449 in the cage is engaged by a roller 447 fixed on shaft 450 which is bearingly mounted on a stator support 448, which roller rolls in the groove 449.

Figure 17shows a compound configuration. Support bearings 451 carry an input shaft 452 and an output shaft 453. The joint has a female elemen 454 with seven waves on a circumferential wavy groove 457. Eight balls 458 engage this groove 457and also engage nine waves on a circumferen¬ tial wavy groove 456on a male element455. It will be apparent that ratios of about 2:1 where a compound unit is used at each end of the angled shaft and where these two compound units ratios are mul iplicatϊve combined ^" , down to ratios of about 1:0.95 for a single simplex unit where there are twenty axial grooves on the female, twenty balls and twenty-one waves on the circumferential wavy groove typically represent the approximate ratio range which can readily be obtained with these drive units.

OΪ.ΪPI

In the constructions of Figures 13 to 17, as in the earlier described arrangements, instead of or in addition to having a symmetrical circumferential wavy groove, the male member may have asymmetric circumferential wavy grooves disposed on lesser circles of the male element. Provision of a plurality of wavy grooves in this way, with the corresponding increased number of balls, results in an increase in the torque handling capacity for a given size of joint. in some of the examples described above, the axial wave driveunit has a constant velocity joint to bring the swashing rotating output back to the axis of the drive or, in the case when the swashing element is not rotating, the constant velocity joint is used to lock it to earth. With high deflection angles, constant velocity joints become highly inefficient so that the e ficiency of the axial wave drive unit is dissipated or partly dissipated in the constant velocity joint. This problem is overcome by the construction shown in Figure 18 in which a second axial wave drive unit is used to bring the drive from the swashing element of a first axial wave drive unit to a rotatable output element.

Referring to Figure 18, there is shown an axial wave drive unit having an input shaft3D1connected to a cran 506with a bearing stud 507running in roller bearings 508 in a part spherical male/female 5 element505. The stud507is at an angle, in this case about 30°, to the axis of the input shaft501so that the stud causes the element 505 to perform a swashing motion when shaft 501is rotated. This swashing action moves part-spherical element 505 between an outer female stator533and a 10 rotating output male element504 hich is connected to an output shaft 502. A circumferential wavy groove 513 on the output male element504and radial grooves 514 on the inside of the ale/female part-spherical element 505 are engaged by balls 510. There is an even number of radial

15 grooves 514 which number is divisible by four and there is an odd number of waves, either one more or one less than the number of radial grooves in the wavy groove 513. The number of balls 510 is equal to the number of radial grooves 514. These balls roll in the radial grooves

20 and in the circumferential wavy groove 513 in the manner described in the aforementioned description. The male/female element505 and male element504thus constitute a first axial wave drive unit. A second unit is formed by a female stator503having radial grooves 511 in which balls

25 59engage, these balls also engaging in the circumferential

OMPI

wavy groove on the exterior of the part-spherical swashing male/female element 5C5.The number of radial grooves 511 is divisible by four and the number of waves in the wavy groove 20 is odd and is either one more or one less than the number of grooves 511. The number of balls is conveniently equal to the number of radial grooves although, as described in the aforementioned specification, the device would be operative if one or a few of the balls were missing. Since the female stator503is fixed, and ° since the part-sphericalπale/fetπale swashing element 505 can rotate relative to the stator503,the male output element 50 _anc i input shaft^Olrthe drive ratio between the input shaft501and the output shaft502is a compound ratio of the ratios of the outer stage axial drive unit and the

^ ⁵ inner stage axial drive unit. The two ratios can be multiplied or divided, one by the other depending if the precessions of the two sets of balls 509 a d 510 relative to the circum erential wavy grooves 512 and 513 are in the same direction or in opposite directions.

2D It will be immediately apparent that, by such a construction, using different ratios for the two axial wave drive units, a very wide range of speed ratios between the input and output shafts may be obtained.

For clarity in Figure 18, no cages have been shown for the two sets of balls but such cages may be provided as described previously.

Figure 19 illustrates a construction using spindles located in needle bearings in one of the members. This use of spindles in bearings can be employed in systems having two axial wave drive stages. Figure 19 illustrates how the construction of Figure 18 can be modified in this way. In Figure 19 the same references are employed as in Figure 18 indicating corresponding components and, in the following description reference will only be made to the descriptive features ofFigure 19. The male member 504 has a wavy groove 522 engaged by a series of spindles 520 in needle bearings 521 arranged around a great circle on the inner surface of the part-spherical male/female element 505. A second set of spindles 523 in bearings 524 carried in the outer female stator 503 engages a wavy groove 525 in the outer surface of the element 505. As in the construction of Figure 18, a compound ratio between the spindles of input shaft 501 and output shaft 502 is obtained, the two ratios being modified cr divided cepending on the relative directions of precessions of the twc sets of spindles in the groove. In the case of spindled configurations, the number of stations for each set of spindles only has to be even and need net be divisible bv four.

OMPI

Another angle drive jo$nt £s shown in Figure 20. This is a two stage angle joint with both stages in the same angle joint instead of two separate joints. This makes it possible to obtain twice the deflection angle and the speed change ratio can Be multiplied or divided. An output shaft 531 is attached to first part spherical male element 532 on wh±ch is cut a circumferential wavy groove 530 in which balls 537 turn. A hollow part- spherical female and male element 533 carries internal arcuate grooves 538 and an external circumferential wavy groove 539. Grooves 538 mesh with balls 537 and the external grooves 539 guide balls 536 ^" which mesh with arcuate grooves in a hollow female part spherical member 536 attached to an output shaft 535. Cages for the two sets of balls are omitted for clarity. The two shafts 531, 535 are supported by bearings 540 in a frame 541 constituting the stator of the assembly.

In the construction of Figure 20, the two planes defined by the two sets of Balls always swash at an angle to one another. This angle does not change and the two planes intersect at the centre point of the system.

From the two stage angle drive joint, there emerges some significant teaching. It becomes possible to make an infinitely variable angle, speed changing drive joint, the angle being variably cylindrically through about 160°, e.g. 80 either side of the direction of the axis of a concentric input output shaft configuration.

To explain how this can be done, consider two parallel shafts which are significantly displaced from each other but in the same plane, if these shafts are connected to one another through two single stage angle drive units and an intermediate connecting shaft, each angle drive unit with a deflection angle of 40 or the complement to it, i.e. 140 and if the housing of one of the angle drive units is rotated through 180 to the axis of the connecting shaft, the two parallel shafts will then be inclined relative to each other at an angle of 80° and will no longer be parallel to each other. If the length of the connecting shaft is reduced to zero, you then, in effect, have a two-stage angle drive joint with infinitely variable angles possible between the input and output shafts. This is. achieved by an outer female member with a concentric inner male member and an intermediate male/ female part sphere. The male/female swashing sphere has, in effect, become the inclined shaft between the two single stage angle drive joints. It is preferred for an inclined thrust plate with a ball thrust bearing to be incorporated, which can be locked at a predetermined radial position, can bear against the male/female sphere to prevent the latter from any inclination to swash instead of to rotate. The housing of the input and output shafts can be hinged relative to each other with the hinge axis passing through the centre point of the male/female sphere. In order to change the angle of the joint, the inclined thrust plate is rotated about the axis of the

CMPI

input shaft until the desired angle is obtained and then locked to the stator housing.

Figures 21 and 22 illustrate this variable angle speed changing drive in two different angular positions. For convenience in illustration, Figure 21 is a plan view of the joint showing the angularly deflected state whilst Figure 22 is an elevation of the joint when the input and output shafts are aligned. A roller bearing 551 in a stator housing 552 supports an input shaft 553 and supports also a concentric inclined thrust plate tube 554. The inclined thrust plate tube 554 is connected to an inclined thrust plate 555. The inclined thrust plate tube 534 has a control arm 556 and a locking screw 557 to enable the thrust plate tube 554 to be locked in any required angular position. A shoulder558 in the tube554 and a ball thrust bearing 559 prevent any axial movement to the left of the inclined thrust plate 555.

The input shaft 553 is connected to a male part- spherical 560 on which is cut a circumferential wavy groove 561 in which run balls 562. A male/female part sphere 563 engages the balls 562 in arcuate grooves on the female side. A ball thrust race 564 runs between one side of the male/female part sphere 563 and a face of the inclined thrust plate 555. A female part- spher 565 attached to an output shaft 566 has arcuate grooves, with balls 567 which in turn mesh with a circumferential wavy groove on the male surface of the

OMFI ^V/I?0

male/female part-sphere 563. The cages for the balls 567 and 562 are omitted for clarity. An output shaft 566 runs in a roller bearing 568 in a swing housing 569. This swing housing 569 is pivotally connected to the stator housing 552 by two sets of hinge plates 570 which pivot about a hinge pin 571.

In order to alter the angular direction of the axis of the output shaft 566 relative to that of the input shaft 553, the control arm 556 is rotated about the axis of input shaft 553 and locked in the desired position by the locking screw 557. It.will be seen that this torque converter thus provides a drive between shafts angularly adjustable in position.

Each axial wave drive stage in the construction of Figures 21 and 22 can be compound or simplex con¬ figuration and the drive ratios can be chosen so that the input shaft and output shaft have the same speeds, or the output can be slower or faster than the input shaft. High efficiency of drive is obtainable because of the pure rolling motion between all torque transmitting elements, regardless of the relative angle of inclination between the input and output shafts. Further configurations of the two-stage device become possible. If we consider the configuration as shown in Figure 18, let us dispense with the input shaft 501 crank 506 and stud 507 and instead, use stator 503 as the input shaft. If the input shaft

is rotated, it will at once cause the male female part sphere 505 to swash. However, it will also cause the output shaft 512 to rotate since it is also swashing relative to male sphere.504. The output speed of the output shaft relative to the--.input speed will be a ratio from the divided or multiplied speed of the two stages.

Figure 23 shows this configuration. An input shaft 581 is attached to a female part sphere 582 which has arcuate grooves meshing with balls 583 which balls mesh in a circumferential wavy groove on the male surface of a male/female part sphere 584. Thε female surface of part sphere 584 has arcuate grooves which mesh with balls 585 in a circumferential wavy groove 586 on a male part sphere 587. The part sphere 587 is attached to an output shaft 588 bearingly mounted in a stator housing 589 as also is the input shaft 581.

Uhere it is desired to haυe tuo concentric output shafts, particularly uhen it is required that they rotate in opposite directions and at equal speeds as for example in contra-rotating propeller driυes in marine, helicopter and airoplane applications, this can easily be done by a simple modification to the configuration in Fig. 18. The stator 503 becomes the second cjtput shaft. The uaυes on the male/female suashing element 505 are arranged to giυe reduction ratios running in opposite directions. If these ratios are equal, and so long as

the torque being applied to each output shaft is equal then the male/female member uill only suash and not rotate. Houeυer, if the ratios are different and/or the tcrque being applied to each output shaft is different, then the male/ female part sphere uill not only suash but it uill also rotate, in order to compensate, so the deυice becomes a torque divider as well as a speed reducer.

Figure 24 shows the above configuration. Inout shaft 631 rotates crank 632 and stud 633 in bearing 634 gyrates male/female part sphere 635 and causes it to swash about part sphere male element 636 which is attached to first output shaft 637. Female surface of male/female part sphere 635 meshes with balls 638 through arcuate grooves on its female surface and circumferential wavy groove 639 on element 636. Balls 640 cause arcuate grooves in a part spherical female element 641 to mesh with circumferential wavy groove on male/female part sphere 635. A second output shaft 642 is attached through bell housing 643 to part spherical female element 641 which is bearingly mounted with said second shaft 642 and input shaft 631 in stator housing 644.

It will also be readily apparent by examining Figure 19 that the spindle configuration replacing the balls and arcuate grooves can be used as an alternative in all the arrangements described with reference to Figures 20 to 24.

From the description of Figure 24, it will be apparent that this configuration can also be employed as a six speed-ratio gear box. The assembly has three shafts. If any one shaft is the input, one of the other shafts may be clutched to the stator and the remaining shaft can be the output shaft. Also, depending on the configuration of the two axial wave drive stages, reverse rotation may be obtained. In all the devices described above torque is trans¬ mitted through a plurality of meshing elements e.g. balls in spindles. In hypocycloidal speed reducers where multitooth engagement is obtained as in the prior quadrant drive configurations, greatly increased torque capacity -becomes possible because of the multitooth engagement. The limitation to torque landling capacity then becomes not the quadrant drive itself but the capacity of the eccentric bearing supporting the gyrating gear. The quadrant drive has a capacity which is about three times greater than the largest bearing that can be accommodated within the gyrating gear on the eccentric shaft.

This problem doesn not arise in an axial wave drive config¬ uration described above since the main ball bearing is part of the main torque transmitting element between the stator and the rotor, and the balls are themselves the torque transmitting elements, and are so disposed about the swashing rotating sphere that all radial and axial

loads on each half of the swashing cycle are equal and opposite. This results in greatly reduced loads on the input and output shaft bearings.

Although a number of constructions using balls have been described, in all simplex constructions it is possible to use spindles instead of balls, as described for example with reference to Figures 9 and 19. With spindles mounted in roller bearings, it is not necessary to equalise the rolling velocities over spherical surfaces. Spindles can thus be put in the male or female member. Using spindles, the angle of swash for a given wave height is halved since each spindle is stationary. Also, only an even number of stations for spindles is required and the number need not be divisible by four.

In a simplex construction, whether using balls or spindles, the length of the arcuate grooves on the female member need not necessarily be equal to the height of the wave on the male member but can be longer or shorter. It s possible to have them shorter than the wave height since the shape of the wavefront can be modified as previously described to give the appropriate path length.

In a compound configuration, if the deflection angle of the balls is more or less than half the angle of swash of the swashing means, the wavefront has steeper or flatter waveform and it is possible to have the waves on the male of a different height from those on the female.

OMPI - Λ IK)